Andreas, regardless of the fact that computing will be dazzlingly different from how it is now in 20 years (which is a given) we can make some pretty sound predictions of what it will NOT be.
Cloud computing is practical, and it will not result in a net loss of jobs, I don't think -- all of those server still need parts, and maintenance, and engineering, and all of the money companies save on IT will go other places. Who lays all the cables that will be needed to network the entire world fast enough for cloud computing to be cost effective vs local computing? Do you have any idea how many people actually need to be connected? How many parts need to be produced for this infrastructure to be developed? I personally believe cloud computing is coming, because it's a safe, logical bet -- it's a cost effective, practical use of resources. But it's going to use an otherworldly amount of resources to make it happen across the entire world. There will be work for a long time. Roles can be rendered obsolete, but the laws of scarcity remain. Everyone will always need things they dont have.
As an side: the singularity is hogwash, unless we start tapping into type 2 level power.
-- which, even if we undergo a science fiction style technological renaissance tomorrow, is going to require years and years of travel and infrastructure development. It expects emulation of the human mind, which is an absolutely absurd notion. Truly abstracting all human life onto hardware is many, many, many many many MANY orders of magnitude more expensive in terms of computing (and consequently, space and energy) than running a server farm.